Why are my corners raising up?

[dustmann]

This seems to be a new issue since I have adopted slic3r 1.2.9. My corners are raising up significantly, and it gets progressively worse with round slopes (e.g. when printing a sphere). It looks like it is extruding too much in the corners, or not retracting enough maybe? I have attached some examples of a perimeter width test (the parts don't quite fit, but I think if I can solve the corner round/overextrusion they may be close).

Edit: I am printing natural PLA at 200* with 60* bed temps and 15% infill with a part cooling fan running at 100% for the duration of the print.

IMG_2920.jpgIMG_2921.jpg

[3DPBuser]

If the rounded part is where it changes layers, might need retracting there.

[Roxy]

So... ABS is worse than PLA. But a lot of times I put an anchor down at corners and use a razor blade to cut it off after a print. I'm bringing up my new printer. It is a G2s Delta. I wanted to change the way the AllenKey Z-Probe was positioned. I had problems even with PLA (And I wanted to use ABS because I need to be safe from high temperatures). I defined corner_anchors as a piece that can be generated. You instantiate the corner_anchors and replicate 6 times. In Slic3r you place one under each leg of the spider. It holds the corners down and when you post process the part you just use a razor blade to cut the extra crap off.

Bring this into OpenScad and you will see what I'm talking about:

include <configuration.scad>


main_ring_height = 8.00;
main_ring_outer_diameter = 60.0;
main_ring_inner_diameter = 40.0;
mounting_hole_size = 4.0;


switch_width = 18.5;
switch_mount_thickness = 3.0;
switch_hole_size = 2.5;
switch_hole_spacing = 9.5;


allen_key_post_depth_size = 9.5;
allen_key_post_face_size = 11;
allen_key_post_height = 17;
coat_hanger_radius = (2.6/2);


delta_arm_thickness = 9.0;
delta_arm_height = 12;
delta_arm_length = 21;
delta_arm_hole_size = 6;
delta_arm_hole_offset = 1;
delta_arm_seperation = 27.5;


center_of_ring = (main_ring_outer_diameter + main_ring_inner_diameter)/2.0 /2.0;




Roxy_Effector();


// Guide Plate to force alignment of Z-Probe


translate([-9,-10,0]) guide_plate();


//translate([30,0,0]) corner_anchor();        // if needed to hold down the legs so they don't lift off of the plate!
                        // We want this part flat!




module Roxy_Effector() {
    difference() {
        union() {
            main_ring();
            switch_mount();
            allen_key_post(); 


            delta_arms_3x();
        }
        switch_mount_holes();
        allen_key_guide(); 
    }
}


module switch_mount_holes() {
        translate([main_ring_inner_diameter/2,switch_hole_spacing/2,main_ring_height/3]) rotate([0,90,0]) 
            cylinder( h=main_ring_height*2, r=switch_hole_size/2.0, $fn=20);
        translate([main_ring_inner_diameter/2,-switch_hole_spacing/2,main_ring_height/3]) rotate([0,90,0]) 
            cylinder( h=main_ring_height*2, r=switch_hole_size/2.0, $fn=20);
}




module main_ring() {
    difference() {
        cylinder( h=main_ring_height, r=main_ring_outer_diameter/2.0, $fn=45);
        translate([0,0,-.1]) cylinder( h=2*main_ring_height, r=main_ring_inner_diameter/2.0, $fn=45);


        for(i=[1:5] ) {
            translate([center_of_ring*cos(i*60), center_of_ring*sin(i*60), -.1]) cylinder(h=25, r=mounting_hole_size/2, $fn=20);
        }
    }
}


module switch_mount()  {
    translate([ (main_ring_outer_diameter/2.0)-switch_mount_thickness, -switch_width/2, 0]) 
        cube([ switch_mount_thickness, switch_width, main_ring_height]);
}




module allen_key_post()  {
    translate([ (main_ring_outer_diameter/2.0)-allen_key_post_depth_size, -allen_key_post_face_size/2, 0]) 
        cube([ allen_key_post_depth_size, allen_key_post_face_size, allen_key_post_height ]);
}




module allen_key_guide()  {
    translate([ (main_ring_outer_diameter/2.0), 0, -1])  {
        hull() {
            cylinder( r=coat_hanger_radius, h=50, $fn=25);    
            translate([-coat_hanger_radius,0,0]) cylinder( r=coat_hanger_radius, h=50, $fn=25);    
        }
        translate([0,coat_hanger_radius/2,allen_key_post_height+coat_hanger_radius]) 
            rotate([0,-90, 35 ]) cylinder( r=coat_hanger_radius, h=15, $fn=20);
    }
}


module delta_arms_3x() {
    for( i=[0:2] ) {
        rotate([0,0,i*120]) delta_arms();


    }
}




module delta_arms()  {
    difference() {
        union() {
            translate([ main_ring_inner_diameter/2, (delta_arm_thickness+delta_arm_seperation)/2,0]) delta_arm();
            translate([ main_ring_inner_diameter/2, -(delta_arm_thickness+delta_arm_seperation)/2,0]) delta_arm();
        }


        translate([ (main_ring_outer_diameter+delta_arm_hole_size)/2+delta_arm_hole_offset, 50, delta_arm_thickness/1.5 ]) 
            rotate([90,0,0]) cylinder(r=delta_arm_hole_size/2, h=100, $fn=25);
    }
}


module delta_arm()  {
    translate([ 0, -delta_arm_thickness/2,0]) 
        difference() {
            hull() {
                cube([delta_arm_length,delta_arm_thickness,main_ring_height]);
                translate([delta_arm_length-.1,0,0]) cube([.1,delta_arm_thickness,delta_arm_height]);
                translate([delta_arm_length/2,0,0]) cube([.1,delta_arm_thickness,delta_arm_height]);
            }
            translate([delta_arm_length,-.1,delta_arm_height/1.4]) rotate([0,-45,0]) cube([20,delta_arm_thickness*1.5,20]);
        }
}








module guide_plate()
{
    difference() {
        union () {
            cube([17,19,1.5]);
            translate([13,15,0]) cube([4,4,7]);
        }
        translate([4,5,-1]) cylinder(r=1.5,h=10,$fn=20);
        translate([4+9.5,5,-1]) cylinder(r=1.5,h=10,$fn=20);
        translate([ 7,9,-1]) cube([3.0,20,15]);
        translate([9,14,-1]) rotate([0,0,45]) cube([8,8,20]);
    }
}






module corner_anchor()
{
    cylinder(h=.35, r=10);
}

[dustmann]

The corners aren't raising off of the bed, they are actually raising "up" off of the top of a print. For example when I print the horseshoe shaped print from the first post, the bottom is perfectly flat, and the top looks like a bedsheet if two people were holding it at the four corners. The middle is approximately 12mm (11.94-12.06), and the outermost edges measure 12.55 causing the top which should be flat to make a "U" shape.

I have mitigated it, but not removed it entirely by changing my default max feedrates to 200,200,2,17 and reverting to default settings in slic3r 1.2.9. Other changes to note (which did not affect print quality): I have upgrade from stock makerfarm firmware to the Marlin release 1.02 firmware, and now I am using the 1.1 RC2 firmware.

Old prints on left, new prints on right.

IMG_2972.jpg

[Alibert]

Looks like over-extrusion to me. At the corners the nozzle has to slow down and speed up again when going in the other direction. If you have a bowden extruder, there is still a lot of pressure in the nozzle which adds extra ooze material there.... ?

It would help if you mention the polymer type, temperatures, direct/bowden etc....

[dustmann]

Ok so I finally fixed this issue. I was able to print the perimeter width model perfectly and slid the components into each other (very tight fit). My cubes are now within a couple of hundredths (i.e. my 10mm cubes are ~9.97-10.02mm) on all sides.

Slicer 1.2.9. seems to over-extrude compared to 1.1.7. My "good" settings ended up being .2mm layer height, .2mm first layer, .5mm default extr width, disabled perimeter overlap, extrusion multi @ .90, 100% 1st layer, 100% top infill, 100% perimeters, 100% external perimeters, .2mm z offset at 205/65C temps